This application will refine and elaborate the psychophysiological assessment procedure for use with Vietnam veterans suffering with Post Traumatic Stress Disorder, to improve its clinical diagnostic capacity and to further develop information regarding etiology. We propose to add a new subject group of Vietnam veterans who suffer from PTSD coincidental with another major psychiatric disorder. Both subject groups will be compared to age and sex matched subjects from the following groups: (1) Vietnam veterans who did not meet the criteria for PTSD; (2) Vietnam-era veterans who did not serve in Vietnam (3) non-veterans and (4) individuals suffering from different anxiety disorders as defined by DSM-III. The comprehensive assessment previously described will be continued. It involves (1) psychologicaland affective states as measured by psychological tests and structured interviews and (2) psychophysiological responses (heart rate, blood pressure, skin temperature, skin resistance and forehead muscle tension level) measured at rest, following mental arithmetic stress and after exposure to an audio tape of combat sounds played at progressively louder sound levels. There will be introduced a biochemical assessment of plasma levels of dopamine, norepinephrine, epinephrine measured by high pressure liquid chromotography taken at rest and short intervals following introduction of the meaningful combat sounds.